The subject matter of the application relates to a stacking device for print products. The device comprises a table on which the print products may be stacked and at least two ejector elements or pushers. The ejector elements may be respectively placed against a stack forming on the table and may push the formed stack away from the table. The device may be furthermore provided with drive elements for operating the two ejector elements.
U.S. Pat. No. 5,868,548A provides a stacking device with two endlessly circulating chains, arranged on a rotating table, with respectively two finger-type ejector elements attached thereto that project in an upward direction. By simultaneously moving respectively one ejector element on each chain, the stack may be pushed away from the table and can thus be ejected. Since the stack simultaneously fits against two ejector elements during the ejection operation, a rotating of the stack on the table is to be avoided. The two chains are driven with the aid of a single motor and are moved synchronously during the ejection operation.
U.S. Pat. No. 5,338,149 discloses a stacking device for which only one ejector element is attached to two chains, moving one above the other, wherein this ejector element acts upon the stack. A different stacking device is disclosed in the U.S. Pat. No. 4,103,785, which is also provided with a single ejector element that acts upon the stack and is mounted on two chains, moving one above the other. Additional stacking devices are disclosed in European patent documents EP-A-0 829 441 and the EP-A-1 362 817, which are commonly owned by the Assignee. However, such devices include a stack lift which requires manual interventions in case of a format change. Further, in known stacking devices, the back length of the print products to be stacked, meaning of the respective stack, may be delimited by adjustable flaps that must be opened and closed. This may result in high stress and extend the cycle time.